Process for breaking petroleum emulsions



Patented Jan. 27, 1953 1 PROCESS FOR BREAKING PETROLEUM EMULSIONS Melvin De Groote, University City, Mo., assignor to Petrolite Corporation, a corporation of Dela- Ware No Drawing. Application December 29, 1950, Serial No. 203,533

11 Claims.

This invention relates to processes or procedures particularly adapted for preventing, breaking or resolving emulsions of the water-inoil type, and particularly petroleum emulsions, the present application being a continuation in part of my co-pending applications Serial Nos. 104,801 and 104,802, both filed July 14, 1949, of which the former is now Patent 2,552,528, granted May 15, 1951, and the latter is now abandoned.

Complementary to the above aspect of the invention herein disclosed, is my companion invention concerned with the new chemical products or compounds used as the demulsifying agents in said aforementioned processes or procedures, as well as the application of such chemical products, compounds, or the like, in various other arts and industries, along with the method for manufacturing said new chemical products or compounds which are of outstanding value in 'demulsification. See my co-pending application Serial No. 203,534, filed December 29, 1950.

My present invention provides an economical and rapid process for resolving petroleum emulsions of the water-in-oil type, that are commonly referred to as cut oil, roily oil, emulsified oil, etc., and which comprise fine droplets of naturally-occurring waters or brines dispersed in a more or less permanent state throughout the oil which constitutes the continuous phase of the emulsion.

It also provides an economical and rapid process for separating emulsions which have been prepared under controlled conditions from mineral oil, such as crude oil and relatively soft waters or weak brines. Controlled emulsification and subsequent demulsification, under the conditions just mentioned, are of significant value in removing impurities, particularly inorganic salts, from pipeline oil.

Demulsification, as contemplated in the present application, includes the preventive step of commingling the demulsifier with the aqueous component which would or might subsequently become either phase of the emulsion in the absence of such precautionary measure. Similarly, such demulsifier may be mixed with the hydrocarbon component.

In my co-pending applications, Serial Nos. 104,801 and 104,802, both filed July 14, 1949, I have described, among other things, the breaking of petroleum emulsions by means of certain polyol ethers. Said invention or inventions described in my aforementioned co-pending applications may be considered, in the broadest aspect, as being concerned with a process for breaking petroleum emulsions of the water-inoil type, characterized by subjecting the emulsion to the action of a demulsifier including high molal oxypro'pylation derivatives of certain polyhydric reactants having molecular weights not above 1200 and at least four hydroxyl groups.

The -pending application above referred to, i. e. Serial No. 104,802, filed July 14, 1949, is concerned with the new derivatives as such without limitation as to any particular use.

The aforementioned co-pending applications included at least one compound, which, although not strictly within the limits defined, still possessed the same distinctive and valuable properties, i. e., oxypropylation derivative of 2-2-6-6- tetramethylolcyclohexanol. This product is made by General Mills, Inc., Minneapolis, Minnesota. For convenience and brevity, it is referred to in the trade, and is described by the manufacturer, as TMC. Hereafter, reference will either be made to TMC or tetramethylolcyclohexanol.

The present invention is concerned with a process for breaking petroleum emulsions by means of a fractional ester obtained from a polycarboxy acid and a pentalol, i. e., a chemical compound having 5 alkanol hydroxyls or the equivalent comparable to diols, trials, and tetralols. The particular hydroxylated compound herein employed is obtained by the oxypropylation of TMC or the simple ethers of TMC (tetramethylolcyclohexanol) by treating said compound with 1 to moles of ethylene oxide or butylene oxide or a mixture thereof. All such derivatives are characterized by having 5 term nal hydroxyl radicals. TMC is depicted thus:

OH Home OHzOH HOHzC CHzOH thus:

R [0010MB] wherein n is a number almost invariably more than one and may be as much as or or more with 10 to 20 as being a representative value. As will be pointed out hereinafter, when the molecular weight of such oxypropylation derivatives on the average reach 3,000 or more, based on the hydroxyl value, the product is at least emulsifiable in kerosene, and frequently, and often not infrequently, perfectly insoluble in kerosene. This is the preferred type of material, and particularly with the further proviso that the molecular weight, based on the hydroxyl value, be between 3,000 and 5,000.

As has been pointed out previously, in a generic sense, the invention involves the ethers obtained by use of ethylene oxide, butylene oxide, etc., as Well as TMC itself.

If one indicates a polycarboxy acid in the following manner:

cooHw in which R is the radical of a polycarboxy acid, as indicated, and which is preferably free from any radicals having more than 8 uninterrupted carbon atoms in a single group, and n is a whole number not greater than 2.

If one mole of the oxypropylated derivative previously described by the formula:

R [omomi] is esterified with a polycarboxy acid, as previously described, in the ratio of 5 moles of the polycarboxy acid or equivalent for each mole of oxypropylated TMC, then the acidic fractional ester so obtained can be indicated by the following formula:

i a [O(RO),.CR"(GOOH),,'

in which the various characters have their previous significance.

Such compound, of course, does not define the invention in its most generic aspect, for the obvious reason that it has not included the ethers of TMC previously described. Furthermore, to a rather small extent an inner ester might be formed, or there may occur some other resultants appearing from some other side reaction.

Summarizing the present invention then, it is concerned with a process for breaking petroleum emulsions of the water-in-oil type, characterized by subjecting the emulsion to the acidic fractional ester obtained by reaction between a polycarboxy acid and oxypropylated tetramethylol cyclohexanol or the penta hydroxylated ethers thereof obtained by treating it with ethylene oxide or butylene oxide in molar ratios in the range of 1 to 10, with the proviso that the oxypropylated compound, prior to esterification, have a molecular weight within the range of 1500 and 6,000. Preferably, the pentahydroxylated compound should be at least emulsifiable in kerosene. The oxypropylated TMC or 'I'MC compound may be used, even though it is kerosene-insoluble, i. e.,

even though its molecular weight is in the low range, for instance, in the neighborhood of 1500 to 1750. Furthermore, it is preferred that the polycarboxy acid have not over 8 carbon atoms. The acidic fractional esters above described are obtained by reacting 5 moles of the polycarboxy reactant with one mole of the pentahydroxylated reactant.

For convenience, what is said hereinafter will be divided into four parts:

Part 1 is concerned with the oxypropylation of tetramethylolcyclohexanol. The same procedure, of course, would be applicable to the hydroxylated ethers above described. In fact, the ethers can be prepared in the same manner from tetramethylolcyclohexanol by use of ethylene oxide or butylene oxide, or a mixture.

Part 2 is concerned with the preparation of the acidic fractional esters from the aforementioned pentalols, i. e., the pentahydroxylated compounds obtained as described in Part 1;

Part 3 is concerned with the use of such oxypropylated derivatives as demulsifiers for petroleum emulsions of the water-in-oil type; and

Part 4 is concerned with other derivatives valuable for various purposes including demulsification but not specifically claimed in theinstant application.

PART 1 For a number of well known reasons equipment, whether laboratory size, semi-pilot plant size, pilot plant size, or large scale size, is not, as a rule, designed for a particular alkylene oxide. Invariably, and inevitably, however, or particularly in the case of laboratory equipment and pilot plant size, the design is such as to use any of the customarily available alkylene oxide, i. e., ethylene oxide, propylene oxide, butylene oxide, glycide, epichlorohydrin, styrene oxide, etc. In the subsequent description of the equipment it becomes obvious that it is adapted for oxyethylation as well as oxypropylation.

Oxypropylations are conducted under a wide variety of conditions, not only in regard to pres ence or absence of catalyst, and the kind of catalyst, but also in regard to the time of reaction, temperature of reaction, speed of reaction, pressure during reaction, etc. For instance, oxyalkylations can be conducted at temperatures up to approximately 200 C. with pressures in about the same range up to about 200 pounds per square inch. They can be conducted also at temperatures approximating the boiling point of water or slightly above, as, for example, to C. Under such circumstances, the pressure will be less than 30 pounds per square inch, unless some special procedure is employed, as is sometimes the case, to wit, keeping an atmosphere of inert gas such as nitrogen in the vessel during the reaction. Such low-temperature-low-reaction rate oxypropylations have been described very completely in U. S. Patent No. 2,448,66l, to H. R. Fife et al., dated September '7, 1948. Low-temperature-low-pressure Oxypropylations are particularly desirable where the compound being subjected to oxypropylation contains one, two, or three points of reaction only, such as monohydric alcohols, glycols and triols.

Since low-pressure-1ow-temperature-low-reaction speed oxypropylations require considerable time, for instance, 1 to '7 days of 24 hours each to complete the reaction, they are conducted, as a rule, whether on a laboratory scale, pilot plant scale, or large scale, so as to operate automatically, The prior figure of seven days applies especially to large-scale operations. I have used conventional equipment with two added automatic features:

(a) A solenoid-controlled valve which shuts ofi the propylene oxide in event that the temperature gets outside a predetermined and set range, for instance, 95 to 120 C.; and

(b) Another solenoid valve which shuts off the propylene oxide (or for that matter ethylene oxide if it is being used) if the pressure gets beyond a predetermined range, such as 25 to 35 pounds.

Otherwise, the equipment is substantially the same as is commonly employed for this purpose where the pressure of reaction is higher, speed of reaction is higher, and time of reaction is much shorter. In such instances such automatic controls are not necessarily used.

Thus, in preparing the various examples I have found it particularly advantageous to use laboratory equipment or pilot plant which is designed to permit continuous oxyalkylation, whether it be oxypropylation or oxyethylation. With certain obvious changes, the equipment can be used also to permit oxyalkylation involving the use of glycide where no pressure is involved,

- making any connections. ":the nitrogen line, which was used to pressure the bomb reservoir. .quired,.any other usual conventional procedure or addition which provided greater safety was used, of course, such as safety glass, protective screens, etc,

except the vapor pressure of a solvent, if any, whichmay have been used as a diluent.

As previously pointed out, the method of using propylene'oxide is the same as ethylene oxide. This point is emphasized only for the reason that the apparatus is so designed and constructed as to use either oxide.

The oxypropylation procedure employed in the preparation of the oxyalkylated derivatives has been uniformly the same, particularly in light of the fact that a continuous automatically-controlled procedure was employed. In this procedure the autoclave was a conventional autoclave made of stainless steel and having a capacity of approximately gallons and a working pressure of one thousand pounds gauge pressure. This pressure obviously is far beyond any requirement as far as propylene oxide goes, unless there is a reaction of explosive violence involved due to accident. The autoclave was equipped with the conventional devices and openings, such as the variable-speed stirrer operating at speeds from 50 R. P. M to 500 R. P. M. thermometer well and thermocouple for mechanic-al thermometer; emptying outlet; pressure gauge, manual vent line; charge hole for initial reactants; at least one connection for introducing the alkylene oxide, such as propylene oxide or ethylene oxide, to the bottom of the autoclave; along with suitable devices for both cooling and heating the autoclave, such as a cooling jacket, and preferably, coils in addition thereto, with the jacket so arranged that it is suitable for heating withv steam or cooling with water and further equipped with electrical heating devices. Such autoclaves are, of course, in essence, small-scale replicas of the usual conventional autoclave used in oxyalkylation procedures. In some instances, in exploratory preparations an autoclave having a smaller capacity, for instance, approximately 3 liters in one case and about 1% gallons in another case, was used.

Continuous operation, or substantially continuous operation, was achieved by the use of a separate container to hold the alkylene oxide be- 5 ing employed, particularly propylene oxide. In conjunction with the smaller autoclaves, the container consists essentially of a laboratory bomb having a capacity of about one-half gallon, or somewhat in excess thereof. In some instances, a larger bomb was used, to wit, one having a capacity of about one gallon. This bomb was equipped, also, with an inlet for charging, and an eductor tube going to the bottom of the container so as to permit discharging of alkylene oxide, in the liquid phase to the autoclave. A bomb having a capacity of about 60 pounds was used in connection with the 1'5-gallon autoclave. Other conventional equipment consists, of course, of the rupture disc, pressure gauge, sight feed glass, thermometer connection for nitrogen for pressuring bomb, etc. The bomb was placed on a. scale during use. The connections between the bomb and the autoclave were flexible stainless steel hose or tubing so that continuous weighings could be made without breaking or This applies also to To the extent that it was re- Attention is directed again to what has been said previously in regard to automatic controls,

which shut off the propylene oxide in event tem perature of reaction passes out of the predetermined range, or if pressure in the autoclave passes out of predetermined range.

With this particular arrangement practically all oxypropylations become uniform, in that the reaction temperature was held Within a few degrees of any selected point, for instance, if C. was selected as the operating temperature the maximum point would be at the most C. or 112 C., and the lower point would be 95 or possibly 98 C. Similarly, the pressure was held at approximately 30 pounds within a 5- pound variation one way or the other, but might drop to practically zero, especially where no solvent such as xylene is employed. The speed of reaction was comparatively slow under such conditions as compared with oxyalkylation at 200 C. Numerous reactions were conducted in which the time varied from one day (24 hours) up to three days (72 hours), for completion of the final member of a series. In some instances, the reaction may take place in considerably less time, i. e., 24 hours or less, as far as a partial oxypropylation is concerned. The minimum time recorded was about a 3-hour period in a single step. Reactions indicated as being complete in 10 hours may have been complete in a lesser period of time in light of the automatic equipment employed. This applies also where the reactions were complete in a shorter period of time, for instance, 4 to 5 hours. In the addition of propylene oxide, in the autoclave equipment as far as possible the valves were set so all the propylene oxide, if fed continuously, would be added at a rate so that the predetermined amount would react Within the first 15 hours of the 24-hour period or two-thirds of any shorter period. This meant that if the reaction was interrupted automatically for a period of time for pressure to drop or temperature to drop, the predetermined amount of oxide would still be added, in most instances, well within the predetermined time period. Sometimes where the addition was a comparatively small amount in a 10-hour period, there would be an unquestionable speeding up of the reaction, by simply repeating the examples and using 3, 4, or 5 hours instead of 10 hours.

When operating at a comparatively high temperature, for instance, between 150 to 200 C., an unreacted alkylene oxide such as propylene oxide, makes its presence felt in the increase in pressure, or the consistency of a higher pressure. However, at a low enough temperature it may happen that the propylene oxide goes in as a liquid. If so, and if it remains unreacted, there is, of course, an inherent danger and appropriate steps must be taken to safeguard against this possibility; if need be a sample must be withdrawn and examined for unreacted propylene oxide. One obvious procedure, of course, is to oxypropylate at a modestly higher temperature, for instance, at to C. Unreacted oxide affects determination of the acetyl 0r hydroxyl value of the hydroxylated compound obtained.

The higher the molecular weight of the compound, i. e., towards the latter stages of reaction, the longer the time required to add a given amount of oxide. One possible explanation is that the molecule, being larger, the opportunity for random reaction is decreased. Inversely, the lower the molecular weight the faster the reaction takes place. For this reason, sometimes at least, increasing the concentration of the catalyst does not appreciably speed up the reaction, particularly when the product subjected to oxyalkylation has a comparatively high molecular weight. However, as has been pointed out previously, operating at a low pressure and a low temperature even in large scale operations as much as a Week or ten days time may lapse to obtain some of the higher molecular weight derivatives from monohydric or dihydric materials.

In a number of operations the counterbalance scale or dial scale holding the propylene oxide bomb was so set that When the predetermined amount of propylene oxide had passed into the reaction, the scale movement through a time operating device was set for either one to two hours so that reaction continued for 1 to 3 hours after the final addition of the last propylene oxide, and thereafter the operation was shut down. This particular device is particularly suitable for use on larger equipment than laboratory size autoclaves, to wit, on semi-pilot plant or pilot plant size, as well as on large scale size. This final stirring period is intended to avoid the presence of unreacted oxide.

In this sort of operation, of course, the temperature range was controlled automatically by either use of cooling water, steam, or electrical heat, so as to raise or lower the temperature. The pressuring of the propylene oxide into the reaction vessel was also automatic insofar that the feed stream was set for a slow continuous run which was shut off in case the pressure passed a predetermined point as previously set out. All the points of design, construction, etc., were conventional including the gauges, check valves and entire equipment. As far as I am aware at least two firms, and possibly three, specialize in autoclave equipment such as I'have employed in the laboratory, and are prepared to furnish equipment of this same kind. Similarly pilot plant equipment is available. This point is simply made as a precaution in the direction of safety. Oxyalkylations, particularly involving ethylene oxide, glycide, propylene oxide, etc., should not be conducted except in equipment specifically designed for the purpose.

Example 1a The starting material was a commercial grade of tetramethylolcyclohexanol. The particular autoclave employed was one with a capacity of gallons or on the average of 120 pounds of reaction mass. The speed of the stirrer could be varied from 150 to 350 R. P. M. Approximately 8.6 pounds of tetramethylolcyclohexanol were charged into the autoclave along with .82 pound of caustic soda. The reaction pot was flushed out with nitrogen. The autoclave was sealed and the automatic devices adjusted for injecting 58.2 pounds of propylene oxide in approximately 10 hours. The pressure was set for a maximum of pounds per square inch. This meant that the bulk of the reaction could take place, and probably did take place, at a lower pressure. The comparatively low pressure was the result of the fact that considerable catalyst was present and also the reaction time was fairly long. The propylene oxide was added comparatively slowly, and more important, the selected temperature range was 205 to 215 F. (approximately the boiling point of water). The initial introduction of propylene oxide was not started until the heating devices had raised the temperature to 8 about the boiling point of water. At the com pletion of the reaction a sample was taken and oxypropylation proceeded as described in Example 2a, following.

Example 2a Approximately 59.7 pounds of reaction mass identified as Example 1a, preceding, were permitted to remain in the reaction vessel, and, without the addition of any more catalyst, 43.02 pounds of propylene oxide were added. The oxypropylation was conducted in substantially the same manner with regard to pressure and temperature, as in Example 1a, preceding, except that the reaction was complete in somewhat less time, i. e., 8 hours instead of 10 hours. At the end of the reaction period part of the reaction mass was withdrawn and employed as a sample, and oxypropylation was continued with the remainder of the reaction mass, as described in Example 3a, following.

Example 3a 63.76 pounds of the reaction mass identified as Example 2a, preceding, were permitted to remain in the reaction vessel. 22.5 pounds of propylene oxide were introduced in this third stage. No additional catalyst was added. The time period was the same as in Example 2a, preceding, to wit, 8 hours. The conditions of temperature and pressure were substantially the same as in Example 1a, preceding. 1

At the completion of the reaction, part of the reaction mass was withdrawn and the remainder subjected to further oxypropylation, as described in Example 4a, following.

Example 4a Example 50 Approximately 61.75 pounds of the reaction mass were permitted to stay in the autoclave. No additional catalyst Was introduced. 17.12 pounds of propylene oxide were added in a 5- hour period. The conditions of reaction in regard to temperature and pressure were substantially the same as in Example 1a, preceding.

Example 6a Approximately 70.87 pounds of the reaction mass were permitted to stay in the autoclave. No additional catalyst was introduced. 22.82 pounds of propylene oxide were added. In this particular instance the addition was very slow, due to the low concentration of catalyst. The time required was 14 hours. The conditions in regard to temperature and pressure were substantially the same as in Example 1a, preceding.

In this particular series of examples, the oxypropylation was stopped at this stage. In other series I have continued the oxypropylation so that the theoretical molecular weight was-approximately 9,000-10,000 and the hydroxyl molec ular weight range from 6,000 to 7,000. Other weights, of course, are obtainable using the same procedure.

Needless to say, the procedure employed to produce oxypropylated derivatives can be employed also to produce oxyethyla-ted derivatives and oxybutylated derivatives of the kind previously described. Such derivatives obtained by treating TMC with 1 to moles of butylene oxide, or a mixture of the two, can then be subjected to oxypropylation in the same manner as illustrated by previous examples so as to yield H 0H5 I (3H4 H products having the same molecular weight characteristics and the same solubility or emulsifi- E H l H H abilityinkerosene. H CE: I on,

What is said herein is presented intabular form 1120 in Table I, immediately following, with some H added information as to molecular weight and as H to solubility of the reaction product in water, C: xylene and kerosene. H I l H TABLE I Composition before Composition at End M. W N T TIL/I13); P535.) Time, TMO Oxide Cato ghee. M gxirtie cet ei F 1 Hours A t., 1 st, lo. 111 m ys sq.m

Ordinarily in oxypropylation, the hydroxyl 35 In the above formulas the larg X i obviously value molecular weight is apt to approximate the theoretical molecular weight based on completeness of reaction, if oxypropylation is conducted slowly and at a comparatively low temperature, as described. In this instance this was true almost .up to approximately 3,000. Note, however, that a variation appears in the oxypropylation of TMC, which is exceptional. The hydroxyl molecular weights were slightly higher in the case of Examples la and 2a than the theoretical molecular weights. One explanation which has been offered, is that one of the hydrogen atoms is labile enough to permit oxypropylation taking place by breaking the bond between a carbon atom and a hydrogen atom. This does take place perhaps in a few peculiar compounds having unusual structure, but would not be expected in this instance. Note also that in the instance of hydroxyl molecular weight of Example 5a, one would hav'expected a value of approximately 4700 and the value obtained wa somewhat less. The value of Example 6a seems to be perfectly normal.

An-oxypropylation of this kind has been repeated,

and in a number of instances, in fact, in the majority of instances, the values came through perfectly ,normal, for instance, as shown by the following table. However, not infrequentl ultimate erratic results of the above kind have been obtained in connection with TMC. No satisfactoryexplanation is offered. A more normal oxypropylation might show values as follows:

Theoretical 0H Molec. Molec. Wt. Weight not intended to signify anything except the central part of a large molecule, whereas, as far as a speculative explanation is concerned, one need only consider the terminal radicals, as shown. Such suggestion is of interest only because it may be a possible explanation of how an increase in hydroxyl value does take place which could be interpreted as a decrease in molecular weight. This matter is considered subsequently in the final paragraphs of the next part, i. e., Part 2.

When acidic esters were prepared from an oxypropylation showing normal values and also from an oxypropylation showing abnormal values to the extent illustrated by the above table, one could not detect any particular difierence in demulsifying effect based on the same hydroxyl value molecular weight.

Referring again to Table I, Examples 1a through 601. were water-insoluble. Examples 1a through 6a were xylenesoluble. Examples 1a and 205 were insoluble in kerosene and Example 3a showed a. very definite tendency to emulsify in kerosene and subsequent Examples 405 through 60. were soluble to emulsifiable in kerosene.

The final products at the end of the oxypropylation step, were somewhat viscous liquids. more viscous than ordinary polypropylene glycols, with a slight amber tint. This color, of course, could be removed, if desired, by means of bleaching clays, filtering chars, or the like. The products were slightly alkaline due to the residual caustic soda. The residual basicity due to the catalyst would be the same if sodium methylate had been employed.

Needless to say, there is no complete conversion of propylene oxide into the desired hydroxylated compounds. This is indicated by the fact that the theoretical molecular weight, based on a statistical average, isgreater than the molecular weight calculated by usual methods, on basis of acetyl or hydroxyl value. This is true even in the case of a normal .run of the kind noted previously. It is true also in regard to the oxypropylation of simple compounds, for instance, pentaerythritol, sorbitol, or the like, which do not show the abnormal characteristics sometimes noted in the oxypropylation of 'IMC.

Actually, there is no completely satisfactory method for determining molecular weights of these types of compounds with a high degree of accuracy when the molecular weights exceed 2,000. In some instances, the acetyl value or hydroxyl value serves as satisfactorily as an index to the molecular weight as any other procedure, subject to the above limitations, and especially in the higher molecular weight range. If any difliculty is encountered in the manufacture of the esters as described in Part 2, the stoichiometrical amount of acid or acid compound should be taken which corresponds to the indicated acetyl or hydroxyl value. This matter has been discussed in the literature and is a matter of common knowledge and requires no further elaboration. In fact, it is illustrated by some of the examples appearing in the patent previously mentioned.

PART 2 As previously pointed out, the present invention is concerned with acidic esters obtained from the oxypropylated derivatives described in Part 1, immediately preceding, and polycarboxy acids, particularly dicarboxy acids such as adipic acid, phthalic acid, or anhydride, succinic acid, diglycollic acid, sebacic acid, azeleic acid, aconitic acid, maleic acid or anhydride, citraconic acid or anhydride, maleic acid or anhydride adducts, as obtained by the Diels-Alder reaction from products such as maleic anhydride, and cyclopentadiene. Such acids should be heat-stable so they are not decomposed during esterification. They may contain as many as 36 carbon atoms, as, for example, the acids obtained by dimerization of unsaturated fatty acids, unsaturated monocarboxy fatty acids, or unsaturated monocarboxy acids having 18 carbon atoms. Reference to the acid in the hereto appended claims obviously includes the anhydrides or any other obvious equivalents. My preference, however, is to use polycarboxy acids having not over 8 carbon atoms.

The production of esters including acid esters (fractional esters) from polycarboxy acids and glycols or other hydroxylated compounds is well known. Needless to say various compounds may be used such as the low molal ester, the anhydride, the acyl chloride, etc. However, for purpose of economy, it is customary to use either the acid or the anhydride. A conventional procedure is employed. On a laboratory scale one can employ a resin pot of the kind described in U. S. Patent 2,499,370, dated March '7, 1950, to De Groote and Keiser, and particularly with one more opening to permit the use of a porous spreader, if hydrochloric acid gas is to be used as a catalyst. Such device or absorption spreader consists of minute alundum thimbles which are connected to a glass tube. One can add a sulfonic acid such as para-toluene sulfonic acid as a catalyst. There is some objection to this, because in some instances there is some evidence that this acid catalyst tends to decompose or rearrange the oxypropylated compounds, and particularly likely to do so if the esterification temperature is too high. In the case of polycarboxyacids such as dlglycollic acid, which is strongly acidic, there is no need to add any catalyst. The use of hydrochloric gas has one advantage over para-toluene sulfonic acid, and that is, that at the end of the reaction, it can be removed by flushing out with nitrogen, whereas, there is no reasonably convenient means available of removing the para-toluene sulfonic acid or other sulfonic acid employed. If hydrochloric acid is employed, one need only pass the gas through at an exceedingly slow rate so as to keep the reaction mass acidic. Only a trace of acid need be present. I have employed hydrochloric acid gas or the aqueous acid itself to eliminate the initial basic material. My preference, however, it to use no catalyst whatsoever and to insure complete dryness of the hydroxylated compound as described in the final procedure just preceding of Table II.

The products obtained in Part 1, preceding, may contain a basic catalyst. As a general procedure, I have added an amount of half-concentrated hydrochloric acid considerably in excess of what is required to neutralize the residual catalyst. The mixture is shaken thoroughly and allowed to stand overnight. It is then filtered and refluxed with the xylene present until the water can be separated in a phase-separating trap. As soon as the product is substantially free from water the distillation stops. This preliminary step can be carried out in the flask to be used for esterification. If there is any further deposition of sodium chloride during the reflux stage, needless to say, a second filtration may be required. In any event, the neutral or slightly acidic solution of the oxypropylated derivatives described in Part 1 is then diluted further with sufficient xylene decalin, petroleum solvent, or the like, so that one has obtained approximately a 45% solution. To this solution there is added a polycarboxylated reactant, as previously described, such as phthalic anhydride, succinic acid, or anhydride, diglycollic acid, etc. The mixture is refluxed until esterification is complete, as indicated by elimination of Water or drop in carboxyl value. Needles to say, if one produces a half-ester from an anhydride such as phthalic. anhydride, no water is eliminated. However, if it is obtained from diglycollic acid, for example, water is eliminated. All such procedures are conventional and have been so thoroughly described in the literature that further consideration will be limited to a few examples and a comprehensive table.

Other procedures for eliminating the basic residual catalyst, if any, can be employed. For

' example, the oxyalkylation can be conducted in absence of a solvent or the solvent removed after oxypropylation. Such oxypropylation end product can then be acidified with just enough concentrated hydrochloric acid to just neutralize the residual basic catalyst. To this product one can then add a small amount of anhydrous sodium sulfate (sufficient in quantity to take up any water that is present) and then subject the mass to centrifugal force so as to eliminate the sodium sulfate and probably the sodium chloride formed.

The clear, somewhat viscous, straw-colored amber liquid so obtained may contain a small amount of sodium sulfate or sodium chloride, but in any event, is perfectly acceptable for esterification in the manner described.

It is to be pointed out that the products here described are not polyesters in the sense that there is a plurality of both hydroxylated compound radicals and acid radicals; the product is 13 characterized by having only one hydroxylated compound radical.

In some instances, and in fact, in many instances, I have found that in spite of the dehydration methods employed above, a mere trace of water still comes through, and that this mere trace of water certainly interferes with the acetyl or hydroxyl value determination, at least when a number of conventional procedures are used and may retard'esterification, particularly when there is no sulfonic acid or hydrochloric acid present as a catalyst. Therefore, I have preferred to use the following procedure: I have employed about 200 grams of the hydroxylated compound, as described in Part 1, preceding; I have added about 60 grams of benzene, and then refluxed this mixture in the glass resin pot, using a phase-separating trap until the benzene carried out all the water present as water of solution or the equivalent. Ordinarily this refluxing temperature is apt to be in the neighborhood of 130 to possibly 150 C. When all this water or moisture has been removed, I also withdraw approximately grams or a little less benzene and then add the required amount of the carboxy reactant and also about 150 grams of a high boiling aromatic petroleum solvent. These solvents are sold by various oil refineries, and, as far as solvent effect, act as if they were almost completely aromatic in character. Typical distillation data in the particular type I have employed and found very satisfactory is the following:

I. B. P., 142 C. m1.,242 C.

5 ml., 200 C. ml., 244 C. 10 ml., 209 C. ml., 248 C. 15 ml., 215 C. ml., 252 C. 20 ml., 216 C. ml., 252 C. 25 1111., 220 C. ml., 260 C. 30 ml., 225 C. ml., 264 C. 35 ml., 230 C. ml., 270 C. 40 ml., 234 C. ml., 280 C. 615 ml., 237 C. ml., 307 C.

After this material is added, refluxing is con- 14 to wit, about to C. If the carboxy reactant is an anhydride, needless to say, no Water of reaction appears; if the carboxy reactant is an acid water of reaction should appear and should be eliminated at the above reaction temperature. If it is not eliminated, I simply separate out another 10 to 20 cc. of benzene by means of the phase-separating trap, and thus raise the temperature to or C., or even to 200 0., if need be. My preference is not to go above 200 C.

The use of such solvent is extremely satisfactory, provided one does not attempt to remove the solvent subsequently, except by vacuum distillation, and provided there is no objection to a little residue. Actually, when these materials are used for a purpose such as demulsification, the solvent might just as well be allowed to remain. If the solvent is to be removed by distillation, and particularly vacuum distillation, then the high boiling aromatic petroleum solvent might well be replaced by some more expensive solvent, such as decalin or an alkylated decalin which has a rather definite or close range boiling point. The removal of the solvent, of course, is purely a conventional procedure and requires no elaboration.

In the appended table Solvent #7-3, which appears in all instances, is a mixture of 7 volumes of the aromatic petroleum solvent previously described and 3 volumes of benzene. This was used, or a similar mixture, in the manner previously described. In a large number of similar examples decalin has been used, but it is my preference to use the above mentioned mixture, and particularly with the preliminary step of removing all the water. If one does not intend to remove the solvent, my preference is to use the petroleum solvent-benzene mixture, although obviously, any of the other mixtures, such as decalin and xylene, can be employed.

The data included in the subsequent tables, i. e., Tables II and III, are self-explanatory, and very complete, and it is believed no further elabtinued, and, of course, is at a high temperature, 45 oration is necessary.

TABLE II M 01. Amt. of Ex. NEx. I h'laheg. 2 Agual BWtd fi Poly.

No. of o. o yaSjc carboxy Acid Oxy. of 6 2 droxyl on g Polyearboxy Reacmnt React- Ester Gmpd. H. C. H 0 Value Actual g a t H- V gr (grs) 1a 1, 705 162. 5 171 l, 740 196 Dialycollic Acid 75. 5 1a 1, 705 162. 5 171 1, 740 196 Phthalic Anhydrid 83. 3 1a 1, 705 162. 5 171 1, 740 199 Maleic Anhyd 55, 9 1a 1, 705 162. 5 171 1, 740 192 Aconitic Acidi 97. 5 1a 1, 705 162. 5 171 1, 740 200 Citraconic Anhyd 64. 5 211 2, 950 95. 2 90 3, 110 199 Diglycollic Acid 42. 9 2a 2, 950 95. 2 90 3, 110 199 Phthalic Anhyd 47, 4 2a 2, 950 95. 2 90 3, 110 202 Malcic Anhydride 31. 8 2a 2, 950 95. 2 90 3, 110 201 Aconitic Acid- 46. 5 2a 2, 950 95. 2 90 3, 110 203 Citraconic Anhyd 36, 4 2a 3, 940 75. 2 81. 6 3, 430 203 Diglycolllc Acid 33. 0 3a 3, 940 75. 2 81. 6 3, 430 199 Phthalic Anhyd 42. 9 3a 3, 940 75. 2 81. 6 3, 430 200 Malcic Anhyd 28. 6 3a 3, 940 75. 2 81. 6 3, 430 199 Aconitie Acid. 50. 5 3a 3, 940 75. 2 81. 6 3, 430 199 Citraconic AnhycL 32. 5 4a 4, 500 62. 3 75. 5 3,810 200 Diglycollic Acid... 35. 2 4a 4, 500 62. 3 75. 5 3, 810 199 Phthalic Anhyd 38, 5 4a 4, 500 62. 3 75. 5 3, 810 201 Maleic Anhyd 25, 8 4a 4, 500 62. 3 75. 5 3, 810 194 Aconitic Acid 44. 4 4a 4, 500 62. 3 75. 5 3, 810 194 Citraconic Anhyd 28.0 5a 5, 770 48. 6 75. 5 3, 710 211 Diglycollic Acid. 37. 8 5a 5, 770 48. 6 75. 5 3, 710 201 Phthalic Anhyd 40. 0 5a 5, 770 48. 6 75. 5 3, 710 201 Maleic Anhyd. 26, 4 5a 5,770 48. 6 75. 5 3,710 200 Aconitic AcitL 47. 0 5a 5, 770 48. 6 75. 5 3, 710 200 Oiti'aeonic Anhyd 30. 2 6a 7, 640 36. 8 53. 8 5, 200 205 Diglycollic Acid 26. 2 6a 7, 640 36.8 53. 8 5, 200 205 Phthalic Anhyd 29. 0 6a 7, 640 36. 8 53. 8 5, 200 203 Maleic Anh. .l l9. 2 6a 7, 640 36.8 53. 8 5, 200 203 Aconitic Acid. 34. 0 6a 7, 640 36. 8 53. 8 5, 200 203 Citraconic Acid 21. 8

TABLE III Esterifica- Ex. No. of Amt. Time of Water Acid Solvent Solvent lgi ggf Esterifica- Out Ester (grs) '0 tion (hrs) (0. o.)

#7-3 252 147 l2. 2 #7-3 279 161 7 l. 0 #7-3 265 138 3% None #7-3 280 155 3% 10. 8 #7-3 265 135 2% None #743 236 153 l 6. 2 #73 2-52 1 55 4% 0. 3 #73 234 165 4% None #73 242 149 2 6. 6 #7-3 238 137 3 None #7-3 241 143 3 1. 7 #7- 3 242 140 4% None #7-3 229 145 1 None #73 245 17s 3% 5. 4 #7-3 232 149 2 None #7-3 230 174 2 4. 8 #7-3 238 143 4% None #7-3 233 134 5 None #7-3 234 178 4% 4. 3 #7-3 223 134 2 None #7-3 244 166 3 5. 6 #73 241 13s 5% None #7-3 227 136 5% None #7-3 242 176 2% 4. 9 #7-3 230 152 2% None #7-3 231 158 3% 3. 8 #7-3 233 136 2 Tone #7-3 220 136 5% None #7-3 239 190 7 3. 1 #73 230 162 3 None The procedure for manufacturing the esters has been illustrated by preceding examples. If, for any reason, reaction does not take place in a manner that is acceptable, attention should be directed to the following details:

(a) Recheck the hydroxyl or acetyl value of the oxypropylated products of the kind specified, and

use a stoichiometrically equivalent amount of acid;

(b) If the reaction does not proceed with reasonable speed, either raise the temperature indicated or else extend the period of time up to 12 or 16 hours, if need be;

(c) If necessary, use /2% of paratoluene sulfonic acid, or some other acid as a catalyst; and

(d) If the esterification does not produce a clear product, a check should be made to see if an inorganic salt such as sodium chloride or sodium sulfate is not precipitating out. Such salt should be eliminated, at least for exploration experimentation, and can be removed by filtering.

Everything else being equal, as the size of the molecule increases and the reactive hydroxyl radical represents a smaller fraction of the entire molecule, thus more difiiculty is involved in obtaining complete esterification. g 7

Even under the most carefully controlled conditions of oxypropylation involving comparatively low temperatures and long time of reaction, there are formed certain compounds whose compositions are still obscure. Such side reaction products can contribute a substantial proportion of the final cogeneric reaction mixture. Various suggestions have been made as to the nature of these compounds, such as being cyclic polymers of propylene oxide, dehydration products with the appearance of a vinyl radical, or isomers of propylene oxide or derivatives thereof, i. e., of an aldehyde, ketone, or allyl alcohol. In some instances, an attempt to react the stoichiometric amount of a polycarboxy acid with the oxypropylated derivative results in an excess of the carboxylated reactant, for the reason that apparently under conditions of reaction less reactive hydroxyl radicals are present than indicated by the hydroxyl value. Under such circumstances, there is simply a residue of the carboxylic reactant which can be removed by filtration, or, if desired, the esterification procedure can be repeated, using an appropriately reduced ratio of carboxylic reactant.

Even the determination of the hydroxyl value by conventional procedure leaves much to be desired, due either to the cogeneric materials previ; ously referred to, or, for that matter, the presence of any inorganic salts or propylene oxide. Obviously, this oxide should be eliminated.

The solvent employed, if any, can be removed from the finished ester by distillation, and particularly vacuum distillation. The final products or liquids are generally from almost water white or pale straw to a light amber in color, and show moderate viscosity. They can be bleached with bleaching clays, filtering chars, and the like. However, for the purpose of demulsification or the like, color is not a factor and decolorization is not justified.

In the above instances I have permitted the solvents to remain present in the final reaction mass. In other instances I have followed the same procedure, using decalin or a mixture of decalin or benzene in the same manner and ultimately removed all the solvents by vacuum distillation.

PART 3 Conventional demulsifying agents employed in the treatment of oil field emulsions are used as such, or after dilution with any suitable solvent, such as water, petroleum hydrocarbons, such as benzene, toluene, xylene, tar acid oil, cresol, anthracene oil, etc. Alcohols, particularly aliphatic alcohols, such as methyl alcohol, ethyl alcohol, denatured alcohol, propyl alcohol, butyl alcohol, hexyl alcohol, octyl alcohol, etc., may be employed as diluents. Miscellaneous solvents such as pine oil, carbon tetrachloride, sulfur dioxide extract obtained in the refining of petroleum, etc., may be employed as diluents. Similarly, the material or materials employed as the demulsifying agent of my process may be admixed with one or more of the solvents customarily used in connection with conventional demulsifyirig agents. Moreover, said material or materials may be used alone or in admixture with other suitable well known classes of demulsifying agents.

It is well known that conventional demulsifying agents may be used in a water-soluble form, or in an oil-soluble form, or in a form exhibiting both oiland water-solubility. Sometimes they may be used in a form which exhibits relatively limited oil-solubility. However, since such reagents are frequently used in a ratio of 1 to 10,000, or 1 to 20,000, or 1 to 30,000, or even 1 to 40,000, or 1 to 50,000 as in desalting practice, such an apparent insolubility in oil and water is not significant, because said reagents undoubtedly have solubility within such concentrations. This same fact is true in regard to the material or materials employed as the demulsifying agent of my process,

In practicing my process for resolving petroleum emulsions oi the water-in-oil type, a treating agent or demulsifying agent of the kind above described is brought into contact with or caused to act upon the emulsion to be treated, in any of the various apparatus now generally used to resolve or break petroleum emulsions with a chemical reagent, the above procedure being used alone or in combination with other demulsifying procedure, such as the electrical dehydration process.

One type of procedure is to accumulate a volume of emulsified oil in a tank and conduct a batch treatment type of demulsification procedure to recover cleanoil. In this procedure the emulsion is admixed with the demulsifier, for example, by agitating the tank of emulsion and slowly dripping demulsifier into the emulsion. In some cases, mixing is achieved by heating the emulsion while dripping in the demulsifier, depending upon the convection currents in the emulsion to produce satisfactory admixture. In a third modification of this type of treatment, a circulating pump withdraws emulsion from, e. g., the bottom of the tank, and reintroduces it into the top of the tank, the demulsifier being added, for example, at the suction side of said circulating pump.

In a second type of treating procedure, the demulsifier is introduced into the well fluids at the well-head or at some point between the well-head and the final oil storage tank, by means of an adjustable proportioning mechanism or proportioning pump. Ordinarily, the flow of fluids through the subsequent lines and fittings suflices to produce the desired degree of mixing of demulsifier and emulsion, although in some instances, additional mixing devices may be introduoed into the flow system. In this general procedure, the system may include various mechanical devices for withdrawing free water, separating entrained water, or accomplishing quiescent settling of the chemicalized emulsion. Heating devices may likewise be incorporated in any of the treating procedures described herein.

A third type of application (down-the-hole) of demulsifier to emulsion is to introduce the demulsifier either periodically or continuously in diluted or undiluted form into the well and to allow it to come to the surface with the well fluids, and then to flow th chemicalized emulsion through any desirable surface equipment, such as employed in the other treating procedures. This particular type of application is decidedly useful when the demulsifier is used in connection with acidification of calcareous oil-bearing strata, especially if suspended in or dissolved in the acid employed for acidification.

In all cases, it will be apparent from the foregoing description, the broad process consists simply in introducing a relatively small proportion of demulsifier into a relatively large proportion of emulsion, admixin the chemical and emulsion either through natural flow or through special apparatus, with or without the application of heat, and allowing the mixture to stand quiescent until the undesirable water content of the emulsion separates and settles from the mass.

The following is a typical installation:

A reservoir to hold the demulsifier of the kind described (diluted or undiluted) is placed at the well-head where the eflluen-t liquids leave the well. This reservoir or container, which may vary from gallons to 50 gallons for convenience, is connected to a proportioning pump which injects the demulsifier dropwise into the fluids leaving the well. Such chemicalized fluids pass through the flowline into a settling tank. The settling tank consists of a tank of any convenient size, for instance, one which will hold amounts of fluid produced in 4 to 24 hours (500 barrels to 2,000 barrels capacity), and in which there is a, perpendicular conduit from the top of the tank to almost the very bottom so as to permit the incoming fluids to pass from the top of the settling tank to the bottom, so that such incoming fluids do not disturb Stratification which takes place during the course of demulsification. The settling tank has two outlets, one

being below the water level to drain oh the water resulting from demulsification or accompanying the emulsion as free water, the other being an oil outlet at the top to permit the passage of dehydrated oil to a second tank, being a storage tank, which holds pipeline or dehydrated oil. If desired, the conduit or pipe which serves to carry the fluids from the well to the ettling tank may include a section of pipe with battles to serve as a mixer, to insure thorough distribution of the demulsifier throughout the fluids, or a heater for raising the temperature of the fluids to some convenient temperature, for instance, to F., or both heater and mixer.

Demulsification procedure is started by simply setting the pump so as to feed a comparatively large ratio of demulsifier, for instance, 1:5,000. As soon as a complete "break or satisfactory demulsification is obtained, the pump is regulated until experience shows that the amount of demulsifier being added is just suflicient to produce clean or dehydrated oil. The amount being fed at such stage is usually 1:l0,000, 1:l5,000. 1:20,000, or the like.

In many instances, the. oxyalkylated products herein specified as demulsifiers can be conven iently used without dilution. However, as previously noted, they may be diluted as desired with ny suitable solvent. For instance, by mixing 75 parts, by weight, of the product of Example 2617 with 15 parts, by weight, of xylene and 10 parts, by weight, of isopropyl alcohol, an excellent demulsifier is obtained. Selection of the solvent will vary, depending upon the solubility characteristics of the oxyalkylated product, and, of course, will be dictated, in part, by economic considerations, i. e., cost.

As noted above, the products herein described may be used not only in diluted form, but also may be used admixed with some other chemical demulsifier.

PART 4 One need not point out the products obtained as intermediates, i. e., the oxypropylation products, can be subjected to a number of other reactions which change the terminal groups, as, for example, reaction of ethylene oxide, butylene oxide, glycide, epiohlorohydrin, etc. Such products still having residual hydroxyl radicals can again be esterified with the same polycarboxy acids described in Part 2 to yield acidic esters, which, in turn, are suitable as demulsifying agents.

Furthermore, such hydroxylated compounds obtained from the polyoxypropylated materials described in Part 2, or for that matter, the very same oxypropylated compounds described in Part 2 without further reaction, can be treated with a number of reactive materials, such as dimethyl sulfate, sulfuric acid, ethylene imine, etc., to yield entirely new compounds. If treated with maleic anhydride, monochloroacetic acid, epiohlorohydrin, etc., one can prepare further obvious variants by (a) reacting the maleic acid ester after esterification of the residual carboxyl radical with sodium bisulfite soas to give a sulfosuccinate. Furthermore, derivatives having a labile chlorine atom such as those obtained from chloroacetic acid or epiohlorohydrin, can be reacted with a tertiary amine to give quaternary ammonium compounds. The acidic esters described herein can, of course, be neutralized with various compounds, so as to alter the water and oil solubility factors, as, .for example, by the use of triethanolamine, cyclohexylamine, etc. All these variations and derivatives have utility in various arts where surface-active materials are of value and particularly are effective as demulsifiers in the resolution of petroleum emulsions, as described in Part 3. They may be employed also as break-inducers in the doctor treatment of sour crude, etc.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A process for breaking petroleum emulsions of the water-in-oil type, characterized by subjecting the emulsion to the action of a demulsifier including hydrophile synthetic products; said hydrophile synthetic products being derived by reaction between (A) Polycarboxy acid; and (B) Hydrophile synthetic products obtained by the oxypropylation of a member of the class consisting or tetramethylolcyclohexanol and the pentahydroxylated ethers thereof obtained in turn by reacting tetramethylolcyclohexanol with an alkylene oxide selected from the class of ethylene oxide and butylene oxide in the ratio of 1 to 10 moles of the oxide for each mole of tetramethylolcyclohexanol, with the proviso that the oxypropylated compound prior to esterification have a molecular weight within the range of 1500 and 6000; the molal ratio of (A) to (B) being 5 to l.

2. A process for breaking petroleum emulsions of the water-in-oil type, characterized by subjecting the emulsion to the action 01 a demulsifier including hydrophile synthetic products; said hydrophile synthetic products being derived by reaction between (A) Polycarboxy acid; and (B) Hydrophile synthetic products obtained by the oxypropylation of a member of the class consisting of tetramethylolcyclohexanol and the pentahydroxylated ethers thereof obtained in turn by reacting tetramethylolcyclohexanol with an alkylene oxide selected from the class of ethylene oxide and butylene oxide in the ratio of 1 to moles of the oxide for each mole of tetramethylolcyclohexanol, with the proviso that the oxypropylated compound prior to esterification have a molecular weight within the range of 1500 and 6000, and be at least self-emulsifiable in kerosene; and the molal ratio of (A) to (B) being 5 to 1.

3. A process for breaking petroleum emulsions of the water-in-oil type, characterized by subjecting the emulsion to the action of a demulsifier including hydrophile synthetic products; said hydrophile synthetic products being derived by reaction between (A) Polycarboxy acid having less than 8 carbon atoms; and (B) I-Iydrophile synthetic products obtained by the oxypropylation of a member of the class consisting of tetramethylolcyclohexanol and the pentahydroxylated ethers thereof obtained in turn by reacting tetramethylolcyclohexanol with an alkylene oxide selected from the class of ethylene oxide and butylene oxide in the ratio of 1 to 10 moles of the oxide for each mole of tetramethylolcyclohexanol, with the proviso that the oxypropylated compound prior to esterification have a molecular weight within the range of 1500 to 6000, and be at least self-emulsifiable in kerosene; and the molal ratio of (A) to (B) being 5 to 1.

4. A process for breaking petroleum emulsions of the water-in-oil type, characterized by subjecting the emulsion to the action of a demulsifier including hydrophile synthetic products; said hydrophile synthetic products being derived by reaction between (A) Polycarboxy acid having less than 8 carbon atoms; and (B) I-Iydrophile,

synthetic products obtained by the oxypropylation of tetramethylolcyclohexanol, and with the proviso that the oxypropylated compound prior to esterification have a molecular weight within the range of 1500 to 6000, and be at least selfemulsifiable in kerosene; and the molal ratio of (A) to (B) being 5 to l.

5. A process for breaking petroleum emulsions of the water-in-oil type, characterized by subjecting the emulsion to the action of a demulsifier including hydrophile synthetic products; said hydrophile synthetic products being an acidic fractional ester of the following formula:

in which the acidic acyl radical is that of a polycarboxy acid having not more than 8 carbon atoms of the structure:

N COOH in which R is the radical of the polycarboxy acid and n is a whole number not greater than 2; and the alcohol radical is that of the pentahydroxylated compound in which R (OH) 5 represents tetramethylolcyclohexanol and (R0) is the divalent propylene oxide radical and n is a whole number so selected that the molecular weight of R [camper] is within the range of 1500 to 6000, with the proviso that said pentahydroxylated compound is at least self-emulsifiable in kerosene.

6. A process for breaking petroleum emulsions of the water-in-oil type, characterized by sub jecting the emulsion to the action of a demulsifier including hydrophile synthetic products; said hydrophile synthetic products being an acidic fractional ester or" the following formula:

in which the acidic acyl radical is that of a dicarboxy acid having not more than 8 carbon atoms and of the structure COOH COOH in which R," is the radical of the dicarboxy acid; and the alcohol radical is that of the pentahydroxylated compound in which R (01-1) 5 represents tetramethylolcyclohexanol and (R0) is the divalent propylene oxide radical and n is a whole number so selected that the molecular weight of 8. The process of claim 6, wherein the dicar boxy acid is maleic acid.

21 22 9. The process of claim 6, wherein the dicarboxy acid is succinic acid. UNITED STATES PATENTS b 10. Th; proete ss of c1aim d6, wherein the dicar- Number Name Date 1S 3 2,295,165 De Groote et a1 Sept. 8, 1942 11. The process of c1a1m 6, wherein the d1car- 5 2,341,846 Memcke Feb. 15, 1944 boxy ac1d 1s dlglycolhc acld. 2357 933 D G t t 1 S t 12 1944 MELVIN DE GROOTE. e r00 6 e a 2,385,970 De Groote et a1 Oct. 2, 1945 2,552,528 De Groote May 15, 1951 FEFERENCES CITED 2,554,667 De Groote May 29, 1951 The followmg references are of record 1n the 10 2552373 Blair 7, 1951 file of this patent: 

1. A PROCESS FOR BREAKING PETROLEUM EMULSIONS OF THE WATER-IN-OIL TYPE, CHARACTERIZED BY SUBJECTING THE EMULSION TO THE ACTION OF A DEMULSIFIER INCLUDING HYDROPHILE SYNTHETIC PRODUCTS; SAID HYDROPHILE SYNTHETIC PRODUCTS BEING DERIVED BY REACTION BETWEEN (A) POLYCARBOXY ACID; AND (B) HYDROPHILE SYNTHETIC PRODUCTS OBTAINED BY THE OXYPROPYLATION OF A MEMBER OF THE CLASS CONSISTING OF TETRAMETHYLOLCYCLOHEXANOL AND THE PENTAHYDROXYLATED ETHERS THEREOF OBTAINED IN TURN BY REACTING TETRAMETHYLOLCYCLOHEXANOL WITH AN ALKYLENE OXIDE SELECTED FROM THE CLASS OF ETHYLENE OXIDE AND BUTYLENE OXIDE IN THE RATIO OF 1 TO 10 MOLES OF THE OXIDE FOR EACH MOLE OF TETRAMETHYLOLCYCLOHEXANOL, WITH THE PROVISO THAT THE OXYPROPYLATED COMPOUND PRIOR TO ESTERIFICATION HAVE A MOLECULAR WEIGHT WITHIN THE RANGE OF 1500 AND 6000: THE MOLAL RATIO OF (A) TO (B) 5 TO
 1. 